Trussed bridge



UNITED sri-iras PATENT carros.

ABRAM S. SW'ARTZ, 0F BUFFALO, NEW YORK.

TRUssED BRIDGE.`

Specification of Letters Patent No. 18,253, dated September 22, 1857.

To all w hom t may concern.'

Be it known that I, ABRAM S. Swanrz,

Tower-Bridges; and I do hereby declarey that the following is a full andexact description thereof, reference being had to the accompanyingdrawings and the letters of reference marked thereon.

The nature of my invention consists in making an iron tower to supportthe arch, the base of which is held against the thrust of the arch, bywrought iron, horizontal tension bars, and the top thereof, by asuspension rod. The tower, the horizontal ten sion bar, and thesuspension rod, whentaken together, make a figure in the form of a rightangled triangle, the foot of the arch resting upon the tower within thistriangle.

To enable others skilled in the art to make and use my invention, I willproceed to describe its construction and operation.

Figure I is a longitudinal elevation of a bridge, of which myimprovement forms a part. Fig. II, is a plan. Fig. III, is an endelevation. Fig. IV, is a side elevation showing the triangle formed bythe tower, tension bar, and suspension rod. It also shows the foot ofthe arch as it rests `on the tower within the triangle; Fig. V,elevation, showing the inside front of the tower.

EpZmmt/on of Fig. I .-A, represents the tower, which is made of castiron. It may be made two and one half feet wide at its base for a spanof from sixty to eighty feetthe width extending parallel up the towertwo and one half feet to the step upon which the arch rests. From thenceit rises seven and a half feet-tapering to eight inches, where thesuspension rod passes through. The metal should be one inch thick andiianges should be cast on each side of both edges. These fianges shouldbe twelve inches wide at the base, and taper to eight inches at top, andone and one fourth of an inch thick. About twelve inches of the top ofthe tower is made beveling, from the back, forward, the bevel angleforming a right angle to the suspension rod c, (as represented at 0".)An opening is made through the tower, opposite and above the step, inorder to lessen the quantity of metal and also to admit a tie rod whichpasses over the arch to be fastened to the tower by means of a screw nutwithin the opening as represented at s. 'Ihe tension bars pass throughthe flanges at the base of the tower, and are secured thereto by meansof heavy screw nuts as represented at n. A cast iron tower of thedimensions herein described will weigh about two thousand pounds. Thedrawings are made on a scale of one fourth of an kinch to one foot. Thesize, form and proportions of the tower as well as all other parts ofthe bridge, may easily be estimated by applying the scale to thedrawings. The towers sustain the whole weight and thrust of the arch.

B, wrought iron tension bar. There are two of these bars to each tower.They eX- tend from tower to tower, and securely hold the base of thetowers against the thrust of the arch. They should be made of the bestquality of wrought iron about two inches in diameter, or of sufficientstrength to resist the strain, which they may be subjected to. Heavyhexagonal screw nuts secure these tension bars to the base of thetowers, as represented at n, n. These bars should be connected to theneedle beams by stirrups, bolts or otherwise for the purpose ofpreventing a vibration of the same.

C, wrought iron suspension rod. This is secured to the top ofthe towerby a heavy hexagonal screw nut, as represented at V. It passes throughthe arch (a slot being made in the arch segmentfor that purpose) andunder the needlebeam at or near the center of the arch, and connectswith the top of the other tower.

If the frame work of the flooring will not allow of a needle beam at thecenter of the arch, then the suspension rod may pass under the two,nearest to the center. The needle beams, under which the suspension rodspass, should rest upon the suspension rod. The suspension rods hold thetop of the tower against the thrust of the arch. The strength of thisrod must be proportioned to the strength of the tension bars, allowingfor its advantage in leverage.

D, arch. This is made of circular seg- Vments of uniform cross section,weighing not less than forty pounds to the lineal foot, and joinedtogether at the ends like a socket joint having one piece extending intothe other, and secured by a flange which is cast on, to guard againstthe side thrust. In case the tie rods herein described, should not beused, then the ends of arch castings should be so shaped as to formvertical holes for the uprights to pass through-cast flat on top, toafford horizontal bearings for the nuts-the holes being so placed, thatthe plane of the arch joint may cut the center of the upright, at theupper side of the casting. The number of arch segments to each arch mustbe determined by the length of the span, and should not be less than tennor more than fourteen feet each. The shape or form, of a cross-sectionof the arch segment, is semicylindrical on top, with the sides extendingdown on a tangent, each in width, one half times the diameter of thecircleand the whole length or girth of the cross section to be about onefourth of an inch to each foot of span. The metal to be not less thanhalf an inch thick in any part, and to be one inch in thickness withintwo inches of the joints.

When the tie rods (e) are used, then the arch segments should be castwith a groove in the crown thereof, so that the tie rods will lie in thegroove, and serve to prevent the arch from swaying. The foo-t of thearch is stepped on to the tower at about two' and one half feet, abovethe base, so that the tower is made to sustain the whole weight andthrust of the arch.

f, diagonal rods, which connect the arch to t-he needle beams; g,vertical rods, connecting needle beams to arch; lL, needle beams; lc,longitudinal joists, with their ends shouldered down and resting uponthe needle beams; an, step, on which the foot of the arch rests; Y,abutment, upon which the tower stands; e, tie rod, lying in the groovein the crown of the arch; s, screw nut, which secures the tie rod to thetower; n heavy hexagonal screw nut which holds or secures the tensionbar to the base of the tower; V, screw nut, which fastens the suspensionrod to the top of the tower; 0, bevel angle.

Explanation of Fig. IL Letters of the same name and kind, refer to likeparts, as in Fig. I.

Explanation 0f Eig. IIL-Letters of the same name and kind refer to likeparts as in each of the other figures.

Explanation of Fig. [T-A, tower; B, tension bar; C, suspension rod.These three parts taken together form a triangle. This triangle embodiesthe principle of my invention whatever may be the height of the tower,or the length of the span. X, represents a cross section of the arch; gvertical rod which passes through the arch, and is held by a screw nut,on the crown of the arch, in case the tie rod is not used. t, is an eyein the Vertical rod which conforms to the groove in the arch. The tierod e, which lies in the groove in the crown of the arch, passes throughthis eye. D, arch, the foot of which rests upon the step, ni, andthrusts against the tower.

Explanation of Eig. V.-This figure is an elevation showing the insidefront or flange projection of the tower y', j. The tension bars B, B,pass through the flange at y', j. ni, step upon which the arch rests; D,arch, or foot of the arch as it rests against the tower.

The size and proportions herein given may be varied and adapted tocircumstances without departing from the principle of my invention.

The arrangement of the parts herein described, so that the tower A, thetension bars B, and the suspension rod C, when taken together willpresent the distinctive feature of a triangle, with the foot of the archD, resting upon the tower within the triangle substantially as hereinset forth.

ABRAM S. SVARTZ.

-Witnesses E. B. FoRBUsH, SAML. SWARTZ.

